Microtesla Nuclear Magnetic Resonance and Imaging with a Superconducting Quantum Interference Device

本文旨在研究超低磁場下的超導量子干涉元件核磁共振與造影；系統使用室溫的接收線圈並將其感測到的核磁共振訊號經由液態氮冷卻的變壓線圈藕和到高溫超導磁量計，待測樣品會先在600高斯的預先極化磁場磁化，再切換到100微米磁場量測；實驗的磁場產生裝置在實驗室自行建造，其中，測量磁場B0是由一組三對線圈組合的改良版Helmholtz線圈，梯度線圈則是由Maxwell對(Gz)，與雙平面線圈(Gx, Gy)等組成，從測量的核磁共振頻譜分析得到測量磁場能在5 x 5米見方的範圍內具有100 ppm的均勻度；此外，與在射頻磁場操作的傳統核磁共振系統相比，超低磁場超導量子干涉元件核磁共振系統在音頻範圍量測，具有電路簡化的優勢。 實驗研究去離子水含磁流體樣品的弛豫特性，透過改變預極化磁場磁化時間測量自旋-晶格弛豫速率(1/T1)，並使用多重自旋回波序列測量自旋-自旋弛豫速率(1/T2) ，結果顯示1/T1與1/T2兩者均與磁流體的磁化率成正比，推測是由於磁流體含量較高的樣品具有較高的磁化率，散佈在去離子水中會破壞局域的磁場均勻度，導致質子間的自旋相位分散，使得弛豫速率增加；實驗最後並以磁流體為對比劑實現T1對比影像，其造影的方法將在文中進一步的說明討論，此結果亦顯示超低磁場超導量子干涉元件核磁共振具有潛力進一步發展為癌症造影的檢驗工具。This work studied nuclear magnetic resonance with a high-Tc superconducting quantum interference device(SQUID) in the microtesla magnetic fields. In the scheme of measurement, the NMR signal was detected by a cooper solenoid at room temperatures and coupled to a very sensitive high-Tc SQUID magnetometer via a cooper transformer at liquid-nitrogen temperature. The samples were pre-polarized at higher magnetic fields, 600 Gauss, and measured at 100 μT magnetic field. In such a low measurement field, apparatus can be easily obtained by homemade. We constructed a three-pair Helmholtz-like coil for Bo measurement field, a Maxwell pair for Gz gradient field, biplanar pairs for Gx and Gy gradient fields. The analysis from the linewidth of NMR spectrum revealed a very uniform measurement field ~ 100 ppm in range of 5 x 5 cm2. Since the measurement field was low as in audio frequency, it takes the advantage of the simplified electronics in contrast to the conventional NMR experiment working with radio-frequency electronics. To demonstrate the potential application of the SQUID NMR/MRI, samples of ferrofluid diluted in water were examined to study the relaxation properties and magnetic resonance imaging. The intensity of spin-echo NMR signal as function of prepolarization time was used to drive the rate of spin-lattice relaxation (1/T1). The rate of spin-spin relaxation (1/T2) was derived by peak strength of multi-echo NMR signals which follow the free induction decay. It was found that both 1/T1 and 1/T2 increase linearly when the magnetic susceptibility χ of SPIO increases by increasing the concentration of SPIO dispersed in water. In an applied field, magnetic moments of SPIO generate microscopic field gradients that weaken the field homogeneity, in turn dephasing the proton’s nuclear spin and enhancing the relaxation rates. A T1-contrast image is demonstrated, using SPIO as the contrast agent and high-Tc superconducting quantum interference devices as the detector. T1-contrast imaging in microtesla fields might provide a potential modality for discriminating cancer

藍芽遙控車

[[abstract]]本專題遙控車是藉由 arduino 遙控零件組裝而成,為了不浪費電子零件資 源及車體輕量化,車體用的是質量輕且不易折損的尼龍板做為基底,程式控制 板選用的是容易上手且功能強大的UNO R3 控制板,此款有許多特色存在,如藍 牙無線模塊,可以和手機藍牙配對遙智慧小車、可接入外部7~12V 的電壓。並 能搭載多款傳感器模塊，根據您的想像力實現各種功能….等等方便且實用的 功能。因應現在車子區是邁向智慧化時代,具有藍芽遙控的功能性,能在各種 危急狀況下,將傷害降到最低,於是我們便想出用最基本且最省成本的零件, 組出一台具有功能性的藍芽遙控車